Foamed polymers have long been used as thermal insulation. The best known of these is polyurethane foam. Also nitrile foams have seen limited use as thermal insulators.
Okey U.S. Pat. No. 4,68,531 describes a composite polyimide foam panel having a thin metal foil bonded to the foamed panel. The panel is said to be fire resistant and have good vibration damping and thermal insulating properties.
Thompson U.S. Pat. No. 3,994,838 describes polyaryloxy phosphazene foams and suggest their use as thermal insulation because of their fire resistance.
Polyorganophosphazenes are known compositions. A polyaryloxyphophazene is described in U.S. Pat. No. 3,856,713. A polyfluoroalkoxyphosphazene is described in U.S. Pat. No. 3,970,533. Methods of curing such polymers by sulfur vulcanization, free-radical (e.g., peroxide) cure and by reaction are well known.